Editing Lycopodiopsida (section)

===Subdivisions===
The PPG I system divides up the extant lycophytes as shown below.
*Class Lycopodiopsida <small>Bartl.</small> (3 orders)
:*Order [[Lycopodiales]] <small>DC. ex Bercht. & J.Presl</small> (1 extant family)
::*Family [[Lycopodiaceae]] <small>P.Beauv.</small> (16 extant genera)
:*Order [[Isoetales]] <small>Prantl</small> (1 extant family)
::*Family [[Isoetaceae]] <small>Dumort.</small> (1 extant genus)
:*Order [[Selaginellales]] <small>Prantl</small> (1 extant family)
::*Family [[Selaginellaceae]] <small>Willk</small> (1 extant genus)

Some extinct groups, such as [[zosterophyll]]s, fall outside the limits of the taxon as defined by the classifications in Table 1 above. However, other extinct groups fall within some [[Circumscription (taxonomy)|circumscriptions]] of this taxon. Taylor et al. (2009) and Mauseth (2014) include a number of extinct orders in their division (phylum) Lycophyta, although they differ on the placement of some genera.<ref name=TaylTaylKrin09/><ref name=Maus14/> The orders included by Taylor et al. are:<ref name=TaylTaylKrin09/>
*Order †[[Drepanophycales]] (including ''[[Baragwanathia]]'', ''[[Drepanophycus]]'' and ''[[Asteroxylon]]'')
*Order †[[Protolepidodendrales]]
*Order †[[Lepidodendrales]]
*Order †[[Pleuromeiales]]
Mauseth uses the order †Asteroxylales, placing ''Baragwanathia'' in the Protolepidodendrales.<ref name=Maus14/>

The relationship between some of these extinct groups and the extant ones was investigated by Kenrick and Crane in 1997. When the genera they used are assigned to orders, their suggested relationship is:{{sfnp|Kenrick|Crane|1997a|p=239}}
{{clade
|1={{clade
   |1=†Drepanophycales (†''[[Asteroxylon]]'', †''[[Baragwanathia]]'', †''[[Drepanophycus]]'')
   |2={{clade
      |1=Lycopodiales
      |2={{clade
         |1=†Protolepidodendrales (†''[[Leclercqia (plant)|Leclercqia]]'', †''[[Minarodendron]]'')
         |2={{clade
            |1=Selaginellales (''[[Selaginella]]'', including subg. ''Stachygynandrum'' and subg. ''Tetragonostachys'')
            |2={{clade
               |1=Isoetales (''[[Isoetes]]'')
               |2=†Lepidodendrales (†''[[Paralycopodites]]'')
               }}
            }}
         }}
      }}
   }}
}}